The optical glass with high refractive index and low dispersion can correct chromatic aberration to miniaturize the optical system, thus it is developed rapidly in recent years. Particularly the market demands on the optical glass with high refractive index and low dispersion, having refractive index nd of 1.78-1.95 and Abbe number vd of 32-50, are increasing.
The formulation system often used for such optical glass is lanthanum borate glass system, but the content of B2O3 and SiO2 as network formers is higher, the refractive index nd of the optical glass may be reduced; but if more ingredients with high refractive index are given to glass in the formulation system, it is very easy to cause the glass stability to be reduced and the glass devitrified in the manufacturing process. Meanwhile, low-cost glass is the direction of improving glass in recent years, and the cost of the raw material GeO2 usually introduced in the previous manufacturing is higher.